Maybe, but instead they added measurements that the event itself shouldn't occur at all in the first place. Since tweets are very short-lived I feel it's more i

Maybe, but instead they added measurements that the event itself shouldn't occur at all in the first place. Since tweets are very short-lived I feel it's more important to proactively prevent spam rather than reactive. Besides that, while it's quite easy to "detect" some spam wave as a human within a given context, implementing such a detection in an automated manner is a lot harder, because a machine doesn't have intuition and have the context required to notice it.